Danielle Ahn and her family hadn't lived in Harriet Tubman for a year before a boy bashed her son's head with a rock for refusing to join a gang.

Her son and the boy who hit him were both in first grade.

"I'm leaving this city," said Ahn, 27. "The violence. The crime. The gangs. It's been rough for my 7-year-old son."

The mother of two is among 137 families still residing at the Harriet Tubman public housing site. She spoke while her friends loaded her U-Haul on Friday. By Saturday, Ahn said, she, her daughter's father, and her two children would be gone.

A year ago, in March 2011, Chattanooga Housing Authority officials announced that the 440-unit site, the second-largest housing development in the city, would be emptied and sold.

More than 150 tenants have vacated, but 137 remain. Some still are waiting for private housing vouchers funded by the federal government; others have vouchers but haven't found landlords who would accept them. And transfer opportunities to other CHA public sites are limited because they're full.

CHA officials say they still haven't found a buyer for Tubman, and the site can't be sold until it is empty.

About 42 families have been relocated to other public housing sites. Ninety families have been relocated locally with private rental vouchers. Five families moved to other places, including Atlanta, North Carolina and Florida. Ahn is moving to Nashville.

It's hard leaving when residents have to find a landlord willing to accept $620 minus about $200 for utilities for a one-bedroom apartment, said Aileen Young.

She said she started looking for a private rental in January and didn't find one until the end of March.

Residents have two months to use their vouchers before they expire. At the end of the two months they may get an extension, CHA officials said.

The price a landlord accepts for a property has a lot to do with location, said Stan Brown, CEO of Success Realty. He owns and manages some properties rented and available to residents with private housing vouchers, a program formerly known as Section 8.

He said he nets $540 a month for a one-bedroom apartment with central heat and air in the Brainerd area.

The demand for affordable housing is so high that a landlord may not be willing to come down to what Section 8 pays, said Brown.

"The government throws in an artificial figure to subsidize a Section 8 recipient. That clashes with supply and demand, and consequently nothing happens," he said.

Young initially was reluctant to leave Harriet Tubman, but after finding a two-bedroom home near North Chamberlain and Bachman in East Chattanooga, she said she can't wait to move.

"You've got to see it," Young said. "A two-bedroom house with three fireplaces. It's to die for. It's perfect."

Ahn said she's also looking forward to moving. She came to Harriet Tubman in November 2010 after a flood forced her from her Nashville apartment. She's using her voucher to rent a house in Nashville.

She plans to enroll in Ball State University, study early childhood education and become a teacher.

"This [the site vacating] has been a blessing in disguise," she said. "I'm getting a Section 8 voucher, and I get to go back home."